It is sometimes desirable to control an electric motor from a location spaced from the motor. In an electric vehicle, for example, an induction traction motor is driven from a battery supply via a power inverter which must be controlled to afford the desired motor speed and direction of rotation. The controller is a microprocessor based module for controlling the motor via the power inverter. A harness comprises wiring necessary for sending control commands to the power inverter. Feedback of motor speed and direction information is necessary input to the controller, and suitable feedback wiring is also part of the harness. To minimize the expense and the complexity of the harness it is desirable to minimize the number of harness wires; thus reducing the feedback wiring is a worthy objective. The benefit of fewer wire is mainly in the relaxed requirement for input and output pins on the controller.